Miniature heat exchanger

ABSTRACT

Covers a heat exchange element for use in a boiler for central heating systems or the like. The heat exchange element includes a boiler section having a passage for water or for any other fluid medium, the passage extending longitudinally and horizontally through the section. The water passage section has a plurality of closely arranged laterally protruding fins formed integrally with the walls of the water passage and they are positioned above horizontally disposed burners which may be supplied with gas.

United States atent 1 Coley et al.

[ 1 3,732,49 51 May 15,1973

[54] MINIATURE HEAT EXCHANGER [75] Inventors: Eric Harry: Coley, Skidby,England;

James Dutfield, Brussels, Belgium [73] Assignee: American Standard Inc.,New York,

[22] Filed: July 30, 1971 [21] App]. No.: 167,763

[52] U.S. Cl. ..122/367 C, 165/181 [51] Int. Cl ..F22b 37/12 [58] Fieldof Search ..165/130, 131,181;

[56] References Cited UNITED STATES PATENTS 10/1944 Wolfetal ..122/3673/1945 Morrow ..122/367 2,739,576 3/1956 Ricardo ..122/233 FOREIGNPATENTS OR APPLICATIONS 512,994 10/1939 Great Britain ..122/367 PrimaryExaminerKenneth W. Sprague Attorney'.lefferson Ehrlich et a1.

[57] ABSTRACT Covers a heat exchange element for use in a boiler forcentral heating systems or the like. The heat exchange element includesa boiler section having a passage for water or for any other fluidmedium, the passage extending longitudinally and horizontally throughthe section. The water passage section has a plurality of closelyarranged laterally protruding fins formed integrally with the walls ofthe water passage and they are positioned above horizontally disposedburners which may be supplied with gas.

7 Claims, 4 Drawing Figures PATENTED RAY I 51975 SHEET 1 OF 3 INVliN'IOA S,

COLEY ERIC H y JAMES DUTFIELD WW4 ATTORNEY Ila :DLLJQD IN VENTORS,

COLEY DUTFIELD ATTORNEY ERIC H. BY JAMES PATEMEUHAYISIQYS 3 732,849

SHEET 3 0F 3 F G INVENTORS,

ERIC H. COLEY BY JAMES DUTFIELD ATTORNEY MINIATURE HEAT EXCHANGER Thisinvention relates to boilers such as are employed in central heatingsystems, and, more particularly, to heat exchange elements for suchboilers. Still more particularly, this invention relates 'to miniatureboilers and also to miniature heat exchange elements for such miniatureboilers.

In accordance with this invention, there is provided, in or for aboiler, a heat exchange element comprising a horizontal section having apassage extending longitudinally of the section between end platesformed integrally with the passage walls, said passage being verticallyelongated throughout the length of the section and having closely spacedlaterally protruding fins externally thereof. Such fins, in theassembled boiler or heat exchange element, will be located abovehorizontally disposed gas burners of the composite boiler.

For a better and clearer understanding of the invention, an embodimentthereof will now be described by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a side view of a heat exchange element shown partly invertical section along the line 1-1 of FIG. 2;

FIG. 2 is an end view of the heat exchange element corresponding to FIG.1, the element being viewed from the left of FIG. 1;

FIG. 3 is plan view, partly in section, along the line III-III of FIG.I; and

FIG. 4 is a front elevational view, partly in section, of a boilerincorporating a heat exchange element substantially in accordance withthe embodiment of FIGS. 1 to 3.

Throughout the drawing the same or similar reference characters will beemployed to designate the same or similar parts wherever they may occurthroughout the drawing.

In order to present a more comprehensive view and understanding of theminiaturized components characteristically employed in this invention,some of the possible dimensions of the components of an exemplary boilersection will b indicated merely for illustration and explanation.Notwithstanding the reference to the dimensions of such components, themore important parameters will necessarily be the ratios of the severalsizes of the several components.

The heat exchange element illustrated in FIGS. 1 to 3 comprises a castiron boiler section 1 (see FIG. 2) having a water passage 2 extendinglongitudinally and horizontally of the section between its end plates 3and 4 (see FIG. 1), the passage 2 forming the waterway of the section.In use, the section is intended to be arranged with its water passage 2extending horizontally and, notwithstanding the height thereof, thesection is accordingly referred to herein as a horizontal section.

The waterway passage 2 is of substantially oblong and of substantiallyrectangular shape in its crosssection as viewed in FIG. 2, the waterpassage being defined by opposite side walls 5, 6, a top wall 7 and acurved bottom wall 8. The water passage 2 is thus of verticallyelongated form, the height of the passage 2 being approximatelysomewhere near or between eight or none times the width thereof, and thehorizontal length of the passage being approximately about twice theheight.

The end plates 3, 4, which are preferably cast integrally. with thewalls of the passage 2, are substantially rectangular in shape (see FIG.2) and are each formed with upper and lower ports 9, 10 for connectionto inlet and outlet pipes, respectively, of a hot water central heatinginstallation. The upper hole or port 9 in end plate 3 is surrounded by aflat bolting-on flange face 1 1 formed with two internallyscrew-threaded holes or ports 12 for receiving bolts of a suitable pipeunion to be secured to the boiler section 1. The lower hole or port 10in end plate 3 is internally screw-threaded to receive an externallythreaded pipe connection. In the boiler section 1 illustrated, the lowerhole or port 10 in end plate 4 (see FIG. 1) has bolting-on flange 11a(shown in dotted lines in FIG. 2) and corresponding screw-threaded holes12, while the upper hole or port 9 in end plate 4 is internallyscrew-threaded for the reception of an externally threaded pipeconnection. It will, of course, be understood that the upper and lowerholes or ports in each end plate may both be provided with bolting-onflanges such as those shown and described.

The waterway passage 2 is also provided internally with longitudinallyspaced pairs of upper and lower strengthening webs 13,14. The side walls5, 6 of the passage 2 are also cast integrally with a plurality oflaterally outwardly extending closely spaced fins 15, these having theirfaces vertically disposed and corresponding substantially in shape tothe end plates but being somewhat smaller in lateral extent. Moreover,the fins 15 have lower edges 16 which may preferably be inclined at anangle of approximately 45 to the vertical, as may be seen more clearlyin FIG. 2. The boiler section 1 is also formed integrally, substantiallymid-way along its length, with reenforcing fins 17. These reenforcingfins 17 are of substantially the same lateral width as the end plates 3,4 and are of a thickness substantially double that of the other fins 15for providing additional strength and additional heat conductivity.

The boiler of this invention, as illustrated in FIG. 4, is especiallysuitable for use in a domestic hot water central heating installation.The boiler comprises a sheet metal back plate which is designated 18 butis not specifically shown, to which a supporting frame 19 is secured.The frame 19 includes side plates, only one of which is shown at 20,between which side plates a horizontal boiler section 21 is mounted. Theboiler section.

21 is similar or substantially identical to that previously describedwith respect to FIGS. 1 to 3, but it may have an end plate 22 providedwith upper and lower boltingon flanges 54, 53. The lower flange 53 hasconnected thereto a pipe union 23 forming a water inlet and the upperflange 54 has connected to it a pipe union 24 forming a water outlet.

Below the horizontal boiler section 21 there extends, at each side, ahorizontal gas-bumer 25, the burner section also being mounted betweenthe side plates (only one of which is shown and designated 20) and beingconnected to a gas supply through appropriate controls indicatedgenerally at 26. Cover plates 27 and 28 are provided for both the boilersection 21 and the gas burners 25 respectively.

In the water pipe line to or from the boiler section 21, there isarranged pump means (not shown) for forcing and pressurizing the waterto be fed through the horizontal passage of the boiler section 21 to beheated to a sufficient or predetermined temperature. In use, the pumpinsures a continuous flow of water under pressure through the horizontalpassage. The heatexchange surfaces provided by the multiplicity ofparallel fins at opposite sides of the water passage 2 serve to insuresatisfactory and efficient heating of the water in the water passage bythe burning gases as the water passes through the finned boiler section21 and thereaft'er passes through the external space to be heated.

The gas burners are spaced below the base of the boiler section 21 topermit an efficient heating of the finned surfaces by the upwardmovement of the flue gases, the spacing in the present embodiment beingequivalent to almost one-half of the overall height of the heat exchangeelement of FIGS. 1 to 3. The arrangement incorporating the relativelynarrow but elongated waterway passage 2 and the construction of fins 15at both sides of the waterway passage 2 develop a high heating output tothe water of the passageway 2 of the boiler section notwithstanding itsrelatively small or miniaturized dimensions.

In the use of the boiler sections 1 or 21, there is a relatively hightemperature difference between the laterally outer tips of the fins l5and the roots thereof nearest the walls of the water passage 2. With aview to counteracting or reducing the stresses that may result from thishigh temperature difference, substantially horizontal saw-cuts or gapsor other slots in the fins 15 may be provided along each side of thesection. These saw-cuts or gaps or other slots 30 may extendtransversely of the fins 15, as shown in FIG. 2, and such slots mayextend to a depth of, for example, approximately two-thirds the width ofthe fins 15, as also shown in FIG. 2.

It will be appreciated that the arrangement shown in FIG. 4 constitutesonly one example of the mode of use of the horizontal heat exchangesection of this invention. A plurality of similar horizontal sectionsmay be arranged in series or in parallel, as desired, to increase theoverall heating capacity by any amount. Moreover, the multiplicity ofhorizontal heat exchange sections, whether arranged in series or inparallel, may readily be incorporated in wall-mounted boilers and otherboiler constructions and such boilers and constructions may embody, as acomposite unit, both a boiler proper and a water reservoir tank forproviding a domestic hot water supply.

The fins 15 at each side of the water passage 2 of the heat exchangeelement are relatively closely spaced and extend outwardly oversufficient distances so as to provide relatively large heat conductingsurfaces. Moreover, the fins 15 extend over substantially the wholeheight of the internal passageway. At each side, each of the fins 15 hasa lateral extend or dimension of almost double the internal width of thewater passage 2. Thus, in a heat exchange element of about cm. inlength, with end plates 3 and 4 of approximately l7.5cm. in height and ll.5cm. in width, positioned as indicated in the drawing, the internaldimensions of the waterway passage 2 may be about 16cm. in height and2cm. in width. Also, the fins 15 corresponding in height to the endplates 3, 4 may have, at each side, a lateral extent or dimension ofabout 3.8cm., a mean thickness of about 0.3cm., and a mean spacing ofabout 0.5cm. The heat exchange element may be made longer or shorterthan that shown in the drawings or described above. Moreover, thesection may be cast in spheroidal graphite iron which is of greaterductility and strength than normal cast iron.

The boiler of this invention, when equipped with one or more heatexchange elements or sections designated 1 or 21, constitutes anefficient, low cost, gas fired, natural draft, balanced flue boiler.Such a boiler is especially adaptable for wall-hung installations on anoutside wall. In one form of construction, the overall cabinetdimensions may be, for example, about 600 mm. (23 5/8) in height, 500mm. (21 5/8") in width, and 300 mm. (11 13/16") in depth.

While this invention has been shown and described in certain particulararrangements merely for illustration and explanation and while certainparticular dimensions and proportions have been recited for aiding inunderstanding the significant parameters of the miniatun'zed heatexchange element of this invention and of the boiler in which suchelement is embodied, it should be clearly understood that this inventionmay be embodied in other and widely varied organizations withoutdeparting from the spirit and scope of this invention.

What is claimed is:

l. A heat exchange element for a boiler having two side walls and frontand rear walls, comprising a single substantially horizontal walledwater passage extending substantially-throughout the horizontal lengthbetween the side walls of the element and extending substantially overthe height of the element but of a width substantially equal to aboutone eighth of the height of the element, the water passage having asubstantially rectangular cross-section, the side walls of which aresubstantially uniform throughout its horizontal length, a plurality ofsubstantially flat relatively thin parallel closely spaced finsintegrally formed with, and extending outwardly from, and perpendicularto, each of the side walls of the water passage substantially over adistance reaching substantially to the outer side walls of the element,and a parallel re-inforcing fin having a means thickness about twicethat of each of the first mentioned fins and located substantiallymidway between the side walls of the element.

2. A heat exchange element for a boiler having two side walls and frontand rear walls, comprising a horizontal, walled water passage extendingsubstantially throughout the horizontal length between the side walls ofthe element but of a width substantially equal to about one eighth ofthe height of the element, a plurality of substantially flat parallelclosely spaced fins integrally formed with, and extending outwardlyfrom, and perpendicularto, each of the side walls of the water passagesubstantially over a distance reaching to the outer side walls of theelement, and reenforcing fins paralleling the first mentioned fins andhaving a mean thickness about twice that of each of the first mentionedfins.

3. A heat exchange element for a boiler according to claim 2 in whicheach of the fins is provided with a horizontal slot extending laterallyfor about two thirds of the width of each fin, each slot being providedabout midway between the top and bottom of the element.

4. A heat exchange element according to claim 3 in which each of thefins has its bottom end tapered along a line about 45 with respect tothe vertical dimension of the water passageway.

5. A heat exchange element according to claim 4 in which each side wallof the water passage is provided with a plurality of horizontal websintegrally formed with the respective walls for reenforcing said walls.

-- mitted, the height of the walled water passage heft-rig about onehalf of the length of the element, the width of the water passage beingabout one-eighth of the height of the heat exchange element, the heatexchange element including a plurality of flat parallel closely spacedfins integrally fonned with the walls of the water passage and extendingoutwardly and perpendicularly from both sides of the walls of the waterpassage substantially to the walls of the heat exchange element, theheat exchange element also including reenforcing fins paralleling theother fins and of greater thickness than the other fins, each of thefins being provided with a horizontal slot extending over abouttwo-thirds of the width of each of the fins and positioned verticallyabout midway between the top and bottom of the element, the inner wallsof the water passage being provided with a series of horizontal websintegrally formed with the walls of the water passage for reenforcingsaid walls.

7. A boiler for a central heating system or the like according to claim6, which includes a plurality of heat exchange elements combined forincreasing the capacity for heating the water flowing through the waterpassages of the heat exchange elements.

1. A heat exchange element for a boiler having two side walls and frontand rear walls, comprising a single substantially horizontal walledwater passage extending substantially throughout the horizontal lengthbetween the side walls of the element and extending substantially overthe height of the element but of a width substantially equal to aboutone eighth of the height of the element, the water passage having asubstantially rectangular cross-section, the side walls of which aresubstantially uniform throughout its horizontal length, a plurality ofsubstantially flat relatively thin parallel closely spaced finsintegrally formed with, and extending outwardly from, and perpendicularto, each of the side walls of the water passage substantially over adistance reaching substantially to the outer side walls of the element,and a parallel re-inforcing fin having a means thickness about twicethat of each of the first mentioned fins and located substantiallymidway between the side walls of the element.
 2. A heat exchange elementfor a boiler having two side walls and front and rear walls, comprisinga horizontal, walled water passage extending substantially throughoutthe horizontal length between the side walls of the element but of awidth substantially equal to about one eighth of the height of theelement, a plurality of substantially flat parallel closely spaced finsintegrally formed with, and extending outwardly from, and perpendicularto, each of the side walls of the water passage substantially over adistance reaching to the outer side walls of the element, andreenforcing fins paralleling the first mentioned fins and having a meanthickness about twice that of each of the first mentioned fins.
 3. Aheat exchange element for a boiler according to claim 2 in which each ofthe fins is provided with a horizontal slot extending laterally forabout two thirds of the width of each fin, each slot being providedabout midway between the top and bottom of the element.
 4. A heatexchange element according to claim 3 in which each of the fins has itsbottom end tapered along a line about 45* with respect to the verticaldimension of the water passageway.
 5. A heat exchange element accordingto claim 4 in which each side wall of the water passage is provided witha plurality of horizontal webs integrally formed with the respectivewalls for reenforcing said walls.
 6. A boiler for a central heatingsystem or the like, comprising a horizontal heat exchange element, a gasburner spaced below the heat exchange element and positionedsubstantially parallel with the heat exchange element, means forsupplying to the heat exchange element pressurized water to be heated,the heat exchange element extending substantially throughout the lengthof the boiler and including a water passage having walls between whichthe supplied pressurized water is transmitted, the height of the walledwater passage being about one half of the length of the element, thewidth of the water passage being about one-eighth of the height of theheat exchange element, the heat exchange element including a pluralityof flat parallel closely spaced fins integrally formed with the walls ofthe water passage and extending outwardly and perpendicularly from bothsides of the walls of the water passage substantially to the walls ofthe heat exchange element, the heat exchange element also includingreenforcing fins paralleling the other fins and of greater thicknessthan the other fins, each of the fins being provided with a horizontalslot extending over about two-thirds of the width of each of the finsand positioned vertically about midway between the top and bottom of theelement, the inner walls of the water passage being provided with aseries of horizontal webs integrally formed with the walls of the waterpassage for reenforcing said walls.
 7. A boiler for a central heatingsystem or the like according to claim 6, which includes a plurality ofheat exchange elements combined for increasing the capacity for heatingthe water flowing through the water passages of the heat exchangeelements.